Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
  • A61K51/02—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by the carrier, i.e. characterised by the agent or material covalently linked or complexing the radioactive nucleus
  • A61K51/04—Organic compounds
  • A61K51/0474—Organic compounds complexes or complex-forming compounds, i.e. wherein a radioactive metal (e.g. 111In3+) is complexed or chelated by, e.g. a N2S2, N3S, NS3, N4 chelating group
  • A61K51/0478—Organic compounds complexes or complex-forming compounds, i.e. wherein a radioactive metal (e.g. 111In3+) is complexed or chelated by, e.g. a N2S2, N3S, NS3, N4 chelating group complexes from non-cyclic ligands, e.g. EDTA, MAG3
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2123/00—Preparations for testing in vivo

Definitions

• Particularly useful chemicals are those which emit gamma radiation. Subsequent scanning of the organ with a gamma ray camera provides an image of the organ from which diagnostic information can be obtained.
• Tc 99m Tc (Tc-99m) has been found to be particularly useful in this area because of its half-life and gamma ray emission.
• Tc-99m compounds have been disclosed for use as positive myocardial imaging agents. These different imaging agents, based on substantially different chemistries, have exhibited varying levels of utility in different mammals. To effectively image the heart the agent must localize in the heart and at the same time rapidly clear from neighboring organs such as the lungs and in particular the liver. Further, the imaging agent must not bind tightly to the blood or else image quality will be poor. An imaging agent which localizes in the heart and at the same time localizes in the liver does not provide a good image of the heart since the apex of the human heart is often obscured by the liver.
• Tc-99m myocardial imaging agents is Deutsch et al U.S. Patent No. 4,795,626. This discloses a type of myocardial imaging agent which due to its ligand system is not reducible in vivo. Thus, the disclosed Tc(III) complexes remain in this oxidation state for imaging purposes. This has been found somewhat useful in myocardial imaging.
• Cardiolite sold by DuPont This is an isonitrile Tc(I) complex.
• the isonitrile ligands contain alkyl ether groups.
• Nuclear Medicine Communication, 10(4), April, 1989, p.245 reports myocardial imaging agents in which 99m Tc is complexed to bidentate phosphorus ligands containing alkyl ether groups. This brief abstract reports a heart/liver ratio of 0.75 which is lower than what is required to obtain a good myocardial image.
• the present invention is premised on the realization that Tc(III) myocardial imaging agents which are not reducible in vivo can be very effective myocardial imaging agents if the ligands contain one or more ether moietes in the ligand system.
• the present invention is premised on the realization that an effective myocardial imaging agent for humans can be prepared by ligating a tetradentate ligand system to the 4 planar coordination bonding sites of an octahedrally coordinated technetium center and bonding ligands containing ether moietes to the axial positions of the technetium center.
• the present invention is premised on the realization that a Tc(III) acac 2 en complex having alkyl ether substituted phosphine ligands at the axial positions provides a commercially viable heart imaging agent.
• Fig. 1 is a graph showing blood clearance from a human volunteer during a stress evaluation of a myocardial imaging agent made according to the present invention.
• Fig. 2 is a graph showing blood clearance from a human volunteer at rest of a myocardial imaging agent made according to the present invention.
• the technetium compounds which are useful as myocardial imaging agents in humans are hexadentate technetium complexes which have an overall cationic charge. More specifically, the complexes will be technetium complexes in the +3 oxidation state coor- dinatively bonded to six atoms as shown in Formula 1.
• R' and R' ' ' represent H, hydroxyl, C 1 -C 5 alkyl, C 1 -C 5 alkyl substituted by hydroxyl, ether, amide, ketone, aldehyde or nitrile group.
• R'' represents C 1 -C 4 alkylene, C 1 -C 4 alkenyl which may be substituted with hydroxyl, ether, amide, ester, ketone, aldehyde or nitrile group.
• the present technetium compound is bonded generally to three ligands, two axial ligands R 1 and R 2 as in Formula 1 and a tetradentate ligand having the following formula:
• suitable tetradentate ligands include N,N'-ethylenebis (tertbutylacetoacetate iminato) hereinafter referred to as (buac) 2 en, N,N'-ethylenebis(benzoylacetone iminato) also referred to as (bzac) 2 en, N,N'-ethylenebis(3- bromoacetyacetone iminato) also referred to as
• Ligands R 1 and R 2 also referred to as the axial ligands represent the same or different ligands both falling within the following general formula:
• R 5 can represent the same moietes represented by R 3 and R 4 above or may in addition represent -OCH 3 , and C 1 -C 4 alkyl.
• R 5 can represent the same moietes represented by R 3 and R 4 above or may in addition represent -OCH 3 , and C 1 -C 4 alkyl.
• Such a ligand can be made according to the following example.
• Standard procedures are used to convert 22.5 grams of 3-methoxy-1-propylchloride (CH 3 OCH 2 CH 2 CH 2 Cl) and 4.9 g Mg metal to the corresponding Grignard reagent in 110 mL tetrahydrofuran.
• To the Grignard reagent cooled in a dry ice acetone bath is slowly added 4.6 g of phosphorus trichloride in 40 mL of tetrahydrofuran.
• the reaction mixture is then allowed to warm to room temperature, and is subsequently heated at reflux for 30 min. This reaction mixture is then cooled to 10°C, and 70 mL of a saturated aqueous solution of ammonium chloride is added. This
• the ligated technetium complex shown in Formula 1 is manufactured in a two step process.
• a 99m-pertechnetate solution is obtained from a 99-Mo generator. This method of obtaining 99m Tc is well known to those skilled in the art and is disclosed for example in Deutsch et al U.S. Pat. No. 4,489,054 incorporated herein by reference. This is also disclosed in Glavan et al U.S. Pat. No. 4,374,821 also incorporated herein by reference.
• This pertechnetate can be diluted to the desired radioactive
• the 99m TcO 4 - (pertechnetate) in which Tc has an oxidation state of +7 is reduced to a technetium +5 complex having a formula 99m Tc v O(L) + . This is formed by heating 99m TcO 4 - in the presence of the
• the 99m Tc v OL + complex is further reduced by treating it with the axial ligand of Formula 3 at slightly elevated temperatures, i.e., heating the 9 9m Tc(V) complex in the presence of the ligand.
• a chemical reducing agent such as borohydride salts, stannous ion salts or hyposulfite salts can also be added.
• the preparation of the Tc(V) complex is further described in Examples 2 and 3 wherein the ligand is (acac) 2 en.
• Pertechnetate is purified according to the method disclosed in U.S. Patent 4,778,672.
• a C18 Sep-pak cartridge was rinsed with 5 mL ethanol and then 3 mL of 0.01M tetrabutylammonium bromide in water.
• a desired amount of 99m TcO 4 - in saline was combined with 1 mL of 0. IM tetrabutylammonium bromide, mixed well, and passed slowly through the C18 Sep-pak.
• the Sep-pak was washed with 10 mL water, 10 mL air were passed through, and the activity eluted with 1-2 mL ethanol.
• a solution of 17 mg H 2 acac 2 en in 0.25 mL is combined with 1 mL of the above tetrabutylammonium 99m-pertechnetate solution and the resulting solution is deaereated for 15 minutes. Then 20 microliters of 1M KOH and 10 microliters of a freshly prepared solution of 30 mg SnCl 2 in 20 mL ethanol are added. The mixture is incubated at 90°C for 15 minutes.
• the mixture was heated for 15 minutes at 90°C and cooled to room temperature.
• the reaction was monitored by HPLC on a PRP-1 column in 90% MeOH/0.01M Na phosphate and 0.01 M Na heptanesulfonate (pH 7.0) at a flow rate of 1 mL/min.
• the Tc(V)O(acac en) cation elutes at 4.0-4.2 min. (As in all cases the positive charge of the cation is offset by a
• a myocardial imaging agent is prepared by reducing the
• Tc(V) complex as prepared in Examples 2 and 3 to a 99m Tc(III) complex.
• the 99m Tc(V) complex is combined with an ether substituted phosphine ligand such as P(CH 2 CH 2 CH 2 OCH 3 ) 3 .
• a solution of the ligand is introduced, at ambient or elevated temperature. This acts to reduce the 99m Tc(V) complex to a 99m Tc(III) complex.
• the Tc(III) complex can then be purified on cationic exchange resin or a reversed phase C 18 Sep-Pak.
• the Tc(III) complex will have the structure of Formula 1. This is further described in Examples 4 and 5.
• 0.3 mL of 0.1M aqueous TMPP.HCl solution from Example 1 is added to the 99m Tc(V) preparation from Example 2 and the mixture incubated for 15 minutes at 70°C.
• the preparation is diluted with 20 mL deareated water (filtering may be needed to remove precipitated ligand) and loaded on a C18 Sep-pak which was prewashed with 5 mL ETOH and 20 mL H 2 O.
• the cartridge is rinsed with 20 mL H 2 O and then twice with 2 mL 80% ethanol-water.
• the compound is eluted in 1-2 mL 80% ethanol-saline.
• Example 3 incubated at 70°C for 15 minutes. This is then ready for use.
• Example 4 about 13 millicuries of 99m Tc activity was injected into a human volunteer under stress (having exercised until the volunteer's heart rate was approximately 80% of maximum predicted by the patient's age and physical condition). Blood samples were then taken immediately after injection and for intervals up to 60 minutes thereafter. The blood clearance data are shown in Fig. 1. Likewise the same test was conducted on a human volunteer at rest and the data are shown in Fig. 2.
• All the 99m Tc(III) complexes described above are administered intravenously as radiopharmaceuticals in a radioactive dose of from 0.01 mCi/ml to 10 mCi/ml most preferably 2 mCi/ml-5mCi/ml.
• the administration dose for humans is usually in the range 10-30 mCi.
• Imaging of the heart can be carried out by scanning techniques after waiting an appropriate period of time to permit blood clearance of the radiopharmaceutical.
• time dependent scintiscans of the chest region of a patient can be used.
• a computer interfaced 16 crystal, Ohio Nuclear Spectrometer can be used for these scans.
• the complexes of the present invention can also be used in single photon emission computed tomography as described in Beyer et al, Diagnostic Nuclear Medicine, Volume 1, No. 2, page 10 (summer of 1984).
• the present invention is particularly suitable for use in a kit preparation.
• the kit preparation would consist of two sterile, pyrogen free vials, the first vial containing an effective ligand having the structure shown in Formula 1 in combination with an effective reducing agent in this case the tin chloride. This would be a lyophilized composition.
• the second vial would contain a protected salt of the phosphine ligand shown in Formula 3. Typically, this would be the phosphine salt bonded to HCl, H 2 SO 4 , iron(II), copper(I) or zinc(II).
• the acid salts are preferred.
• the kit would be used by injecting the purified 99m-pertechnetate obtained from a molybdenum generator into the first vial.
• the 99m Tc(III) complexes of the present invention provide a radiopharmaceutical uniquely adapted for use in myocardial imaging of humans.
• radiopharmaceuticals neither hang up in the blood system nor the liver and yet bind to the heart for long periods of time ( 5h) to provide useful positive human heart images.

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• 1989
  • 1989-05-19 US US07/354,491 patent/US4917879A/en not_active Expired - Fee Related
• 1990
  • 1990-03-20 EP EP90910036A patent/EP0472665B1/de not_active Expired - Lifetime
  • 1990-03-20 ES ES90910036T patent/ES2058922T3/es not_active Expired - Lifetime
  • 1990-03-20 JP JP2509078A patent/JPH0776182B2/ja not_active Expired - Lifetime
  • 1990-03-20 AU AU58453/90A patent/AU633597B2/en not_active Ceased
  • 1990-03-20 CA CA002051699A patent/CA2051699A1/en not_active Abandoned
  • 1990-03-20 DK DK90910036.4T patent/DK0472665T3/da active
  • 1990-03-20 WO PCT/US1990/001497 patent/WO1990014106A2/en active IP Right Grant
  • 1990-03-20 DE DE90910036T patent/DE69002627T2/de not_active Expired - Fee Related
  • 1990-03-20 AT AT90910036T patent/ATE92341T1/de not_active IP Right Cessation

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